Spinnerets and methods of making them



Nov. 17, 1964 T. WALTON, JR 3,156,950

SPINNERETS AND METHODS OF MAKING THEM Filed May 9, 1962 2 Sheets-Sheet lo o o o 1964 T. WALTON, JR 3,156,950

SPINNERETS AND METHODS OF MAKING THEM Filed May 9, 1962 2 Sheets-Sheet 2United States Patent 3,156,950 SPINNERETS AND WTHUDS OF MAKING '5? EMThomas Walton, In, Qolwiclr, Cherry Hill, N.J., assignor to Eohm 8r Haas(Company, lhiladelphia, Pa, a corporation of Delaware Filed May 9, 1%2,Ser. No. 1%,466 7 Claims. (Si. 18-45) The present invention is concernedwith multi-hole spinnerets and methods of making them. It isparticularly concerned with a novel and improved spinneret and animproved method for producing spinnerets of this type in an eificientand inexpensive manner.

It is known and quite common practice to produce spinnerets by drillingthe holes in plates of suitable material and thickness such as of thincorrosion-resistant metals or of glass or ceramic plates of variousthicknesses. It is also known to mount wires in a molten material suchas glass or metal of different composition than the wire andsubsequently subject the mounting to a material, such as an acid, whichcorrodes and eats out the wire While leaving the surrounding glass ormetal mounting material. Both of these processes are of time-consumingand expensive character. Both of these methods are particularlyexpensive and laborious when it is desired to provide spinnerets havinglong bores which are of special advantage in particular types ofspinning operations.

It is an object of the present invention to provide multihole spinneretshaving capillary openings which may have any desired length of bore ofuniform diameter. It is also an object of the present invention toprovide a simple, rapid, eiilcient, and inexpensive method of producinga multi-hole spinneret regardless of the length of the orifices or holestherein.

It is also an object of the invention to provide improved spinnerets andmethods of making them adapted to accommodate large numbers of holes andhaving great versatility in respect to spacing, length and diameter oforifice passage, and also as to the materials from which the spinne-retis formed.

In the drawing which is illustrative of the present invention,

FIGURE 1 is a face view, greatly enlarged, of a portion of spinneret ofthe present invention,

FIGURE 2 is an enlargement of a portion URE 1,

FIGURE 3 is an enlargement of a portion of a similar face View of amodification,

FIGURE 4 is a longitudinal section of an assemblage of capillary tubesshowing one stage of the method of manufacture,

FIGURE 5 is another longitudinal section similar to that of FIGURE 4 butshowing a modification,

FIGURE 6 is a face view of a template, having bored or etched openings,

FIGURE 6a is a longitudinal section of the capillary tube assembly atone stage of the manufacture of template spinnerets,

FIGURE 7 is an end view of a capillary tube assembly using a woventemplate,

FIGURE 8 is an end view of a Water type capillary tube assembly,

FIGURE 9 is a modification of the wafer method of producing spinneretsshowing two Wafer sections assembled together,

FIGURE 10 is a longitudinal section showing one way of mounting thespinneret of the present invention,

FIGURE 11 is a longitudinal section of a modified mounting system forthe spinneret of the present invention, and

of FIG- FIGURE 12 illustrates another modification of a mountingarrangement.

In general the spinneret of the present invention comprises a pluralityof adjacent capillary tubes parallel to one another, united by a cementdisposed between the outer walls of the adjacent tubes, into an integralunit having the passages or channels of the tubes extending between andopening into terminal faces of the unit. The diameter of the passagesmay be from about 0.05 to 0.3 mm. and the space between the peripheriesof adjacent openings of the orifices may be from about 0.038 to about0.8 mm. or greater. The length of the capillary passage may vary widely.For most practical purposes, lengths of 0.75 to or more millimeters maybe employed and preferred spinnerets have passages of a length fromabout 5 to 15 mm.

As shown in FIGURE 1, the spinneret comprises a plurality of individualtubes 2 having capillary passages or channels 3, the tubes being adheredtogether by any suitable cement 4.

FIGURE 2, having a greater enlargement, gives the construction inclearer detail.

The spacing between adjacent orifices or passages may be varied by usingcapillary tubes having greater or less wall thickness. Alternatively, asshown in FIGURE 3, solid rods 2:: may be interposed between the tubes 2.The rods 2a may be any suitable cross-sectional shape such as square,hexagonal, or circular (as shown) and may be of any suitable thicknessor diameter. For example, they may be of 0.12 to 0.8 mm. in thickness oriameter. Instead of interposing rods, the tubes may be spaced by relyingupon the use of extra cement 4 to hold the tubes apart the desireddistance. The spacing may be controlled by the use of bored, etched, orwoven templates 36 (FIGURES 5, 6 and 7) as will become apparent from thedescription hereinafter.

The spinnerets of the present invention may be made by assembling anydesired number of tubes having capillary passages, which tubes may beformed of any material such as glass or metal within an outer sheath orjacket 5 (see FIGURE 4). The tubes may be of any length, such as from 5to mm. or more. After assembling, the tubes are cemented together andthe unitary body, having parallel passages therethrough, is then cut atintervals transversely with a suitable rotary knife or abrasive wheel toprovide unitary spinneret bodies having any desired length of passage.The sheath may be of any cross-sectional contour, such as hexagonal,oval, or circular, as shown. The sheath may be of various thicknesses.For example, if of metal, it may range from 0.25 to 3.5 mm. thick, andif of plastic, glass, or ceramic material, about 1.25 to 6 mm. thick.

The bundle o5 tubes may number from a few, such as a half-dozen to adozen, to hundreds or thousands (eg. 30,000 to 59,000), the overallwidth or diameter of the face of the resulting spinneret being fromabout an eighth of an inch to 3 inches or more. Using glass capillarytubes commercially available having an outer diameter of 0.4 mm. and aninside or passage diameter of 0.19 mm., a practical spinneret having 200holes requires only a face diameter of 9.5 mm. Comparable compactness isobtained from stainless steel tubing, commonly employed for the makingof hypodermic needles.

As shown in FIGURE 4 the bundle of tubes 2 are disposed parallel to oneanother and inserted with their closed ends 6 into the sheath 5. Eitherbefore or after insertion of the tubes 2 into the sheath 5 any suitablecement in liquid or powdered solid form may be introduced within thesheath 5 between the tubes. For example, the sheath 5 may be disposed ona plug: 7 which serves to close the end of the sheath during insertionof the tubes and cement. Then a liquid adhesive or cement may beintroduced into the sheath above the plate after which the tubes areinserted. The insertion of the tubes 2 forces the cement upwardly untilit reaches the top of, or overflows, the sheath 5. The cement, afterremoval of any excess from the outside of the sheath, can then be driedor cured by heating or allowed to cool, if it is simply in moltencondition, to set and unite the several tubes into a unitary assembly.Thereafter, the assembly is cut at intervals transversely.

The invention is not limited to any particular cement as numerousthermoplastic or lthermosetting materials can be employed includingphenoplasts, aminoplasts, polyepoxides, and vinyl resins. Simplethermoplastic materials may be used in molten condition and allowed tosolidify. Polyvinyl chlorides, or plastisols containing them, with orwithout cross-linkers are quite useful. Thermosetting materials mayinclude suitable catalysts to assist the curing and may be heated asdesired. Cold setting adhesives may be employed. Molten salts, such assilver chloride, and oxides, such as magnesium oxide, are also useful.

If desired, the cement employed may be a powdered glass frit. Afterassembling the tubes within the sheath and disposing the frit betweenthe tubes, the whole assemblage may then be subjected to heat to fusethe frit and cause it to cement the tubes together. When such a fusiblehit is used with glass capillary tubes it should, of course, have alower fusing temperature than that of the tubes so that the tubes arenot distorted as a result of heating to fuse the frit.

The cement, which may be termed a mounting material or uniting medium,should be chosen so that it does not have so great a difference in heatexpansion coefficient with respect to the material of the tubes (andwhen the sheath is to be permanently joined also, with re spect to thesheath) that the unitary spinneret does not retain its integrity underthe conditions, especially the term perature of use.

The material of the spinneret, i.e., the tubes, cement, and sheathshould be chosen to resist corrosion under the conditions of spinningwhich may often involve strongly acidic or alkaline spinning dopes orcoagulating baths.

FIGURE shows a modification in which a foraminous plate or template 36is disposed at each end of the sheath 5a. The tubes 2 are inserted intothe holes 701 of the templates (which holes may be bored or etched) andthe cementitious material is then supplied through suitable extraopenings 7a in the top template in order to fill the space around thetubes 2 and between the templates.

FIGURE 5 also shows a modification in which the sheath is provided atintervals with circumferential rings or ribs 8. These rings are spacedapart by distances corresponding to the length of spinneret bore desiredso that each spinneret is provided with at least one such ring tofacilitate mounting as shown in FIGURE 11.

After the cement sets, the assemblage of FIGURE 4 or 5 is cuttransversely at intervals to provide the spinneret units. The points ofcutting of the embodiment of FIG- URE 5 may be chosen to place the rib 3at one end of each unit or in the middle thereof. Again, the assemblagemay be cut through the ribs 8 to provide a reinforcing ring at each endintsead of merely at one end or somewhere in the middle.

The cement employed may be one which adheres the tubes to the inside ofthe sheath 5 so that the sheath 5 forms an integral part of theassemblage. On the other hand a cement may be employed which does notadhere to the interior of the sheath so that after it is set thecapillary tube assemblage may be withdrawn from Within the sheath. Theuse of a release agent coated upon the interior surface of the sheathmay, in this instance, be helpful but it is unnecessary in most cases.

Generally, it is preferred to adhere the tubes having the capillarypassages to the interior of a suitable sheath so that the latterprovides a protective mounting support.

The capillary tubes 2 may be formed of metal, especially suchcorrosion-resistant metals as platinum, palladium, rhodium and alloysthereof, also nickel, Monel metal and stainless steel, or they may beformed of siliceous materials such as silica or glass. The sheath may beformed of metal, glass, crown of plastic or resinous material, such aspolyvinyl chloride, polyethylene, nylon, and polyethylene glycolterephthalate.

After setting of the cement to unite the tubes together with or Withoutthe sheath adhering thereto, the assemblage is cut transversely toremove the closed ends 6 and the sections of the assemblage are cut offat spaced intervals depending upon the length of bore desired in thespinneret.

When the capillary tubes are of metal, it is possible to cut theassemblage to provide capillary passages as short as 0.8 mm. However,with glass it is generally preferred to have a length of passage atleast about 3 FIGURE 7 shows a woven template in which the spacingelements 7b may be the interwoven wire rods of a wire fabric.

FIGURE 8 shows a simple multi-hole spinneret formed by cementing asingle row of parallel capillary tubes together to provide a thin wafer,which is cut transversely to provide spinnerets having passages orchannels of any desired length.

A spinneret may be formed by assembling a plurality of such wafers, asin FIGURE 9, wherein two are cemented together. As in the otherembodiments, the spacing between the spinneret holes or passages may beincreased as desired by the insertion of solid rods 2a wherever desired.

FIGURE 10 shows one form of mounting in which a spinneret 9 havingpassages with a relatively great length is used. The spinneret unit 9 inthis case is of cylindrical shape having a uniform outer diameter aswould be obtained by cutting the assemblage of FIGURE 4 at intervals. Aflexible plastic or rubber ring or ferrule it is slipped about thespinneret body 9 so that it grips the spinneret firmly. A fitting 11 ismounted on the feed pipe 12 for the material to be spun, making athreaded engagement therewith at 13. The fitting 11 is provided with acentral bore or chamber receiving one end of the spinneret 9. Thefitting 11 also has a tapered annular surface at 14 adapted to receivethe annular sealing gasket 15 of rubber or other resilient materialwhich is pressed against the ferrule 10.

A coupling unit 16 having a central bore or channel of suitable size toreceive the spinneret unit 9 and having an inwardly facing taperedannular surface 17 has an internal threaded opening at 18 adapted toengage an outer threading 19 of the fitting 11. By tightening thecoupling 16, the ferrule 15) is forced under pressure to engage and holdthe spinneret 9 in fixed position.

In FIGURE 11 the flanged or ribbed type of spinneret unit 9a as obtainedfrom the system shown in FIGURE 5 is mounted by insertion of one endwithin a pipe 12a adapted to supply the material to be spun to thespinneret.

A sealing gasket 20 is positioned between one end of the flange 8 andthe end of the pipe 12a. A coupling unit 21 has an inwardly extendingflange 22 adapted to surround the spinneret unit 9 and to engage the ribor flange 8. The ring 22 tightly engages the ring 8 when the couplingZlis screwed at 23 upon the pipe 12a.

FIGURE 12 shows a mounting assembly in which a thin plate or spinneretbody 9b having orifices of short length is mounted. This short-borespinneret plate 9b is held within a coupling unit 24 which has aninwardly extending rim or flange 25 which presses the plate against asealing gasket 26, seated against the outer face of the mounting unit27. The unit 27 is threadedly engaged upon the feed pipe 28 for thematerial to be spunand the coupling unit 24 also threadedly engages themounting unit 27.

The spinnerets are useful for the spinning of a wide variety ofmaterials. Such materials include viscose, cupramrnonium cellulose,casein solutions, solutions of vinyl resins including copolymers ofvinyl chloride and vinyl acetate, as well as acrylonitrile polymersespecially those containing at least 70% by weight of acrylonitrile,cellulose others such as cellulose acetate or cellulose acetatebutyrate, cellulose others such as ethyl cellulose, and polyamidenylons. They are also useful for the melt-spinning of nylon,polyethylene glycol terephthalate, and vinyl resins such as thecopolymers mentioned above. They are also useful in the dry spinning andwet spinning of any of the solutions mentioned hereinabove. Thespinnerets of the present invention are also especially useful for thespinning of aqueous emulsion polymer dispersions whether the polymer isof polar or non-polar character. Thus, it may be employed for thespinning of rubber and synthetic rubber latices including those ofbutadienestyrene and butadiene-acrylonitrile polymers, polystyrene,polyethylene, and polypropylene, and the polar polymers disclosed in US.Patent 2,914,376.

The following examples illustrate the preparation of preferredembodiments by the method of the present invention.

Example 1 A stopper is inserted into one end of a length of a glass tubehaving an outside diameter of 1 cm. and a Wall thickness of 1 mm. Aviscous cement of a mixture of sodium silico-fiuoride and finely-ground(200 mesh-Standard Tyler screen size) softer solder high density glassfrit is poured into the glass tube. Then 260 precision glass capillarytubes (0.15 mm. inside diameter (I.D.) and 0.35 mm. outside diameter(G.D.)) are closed at both ends by quickly heating the ends in the flameof a laboratory gas burner and inserted endwise several at a time intothe cement until they touch the inside Wall of the stopper and projectabout 2 to 3 mm. from the open end of the large tube. Excess cement iswiped from the outside of the large tube or sheath. The cement isallowed to harden for 24 hours. The assembly is then cut transversely atthe desired spaced intervals with a carborundum wheel of soft varietywhich allows the particles to erode easily during cutting. Duringcutting, water is directed over the wheel to flush the particles and toprevent clogging of the passages of the capillary tubes. Then the cutfaces are ground and polished while forcing Water or compressed gasthrough the capillary passages to prevent clogging by accumulation ofdebris. The f'mished spinneret thereby obtained can be used in one ofthe mountings of FIGURES to 12.

Example 2 One end of a soft glass sheath (4 mm. ID. and 1 cm. 0.1).) 9cm. long is closed by heating in a gas flame and fusing the end. Then200 (10 cm. long) commercially available precision-bore glass capillarytubes of the R-6 standard flint type (0.2 mm. 1.1).) are closed at eachend by heating quickly to minimize the tendency to form a knob on theends. These tubes are then fully inserted endwise into the larger glasssheath so that they protrude about 1 cm. beyond the open end of thesheath. The assembly is subjected to the action of a mechanical vibratorWhile the protruding ends are surrounded and covered with afinely-ground (260 mesh) lead solder sealing glass (such as of the typeNo. 7570, Corning Glass Works). After the interstitial spaces of theassembly are filled with the soft glass frit, additional frit is placedaround the projecting ends of the capillary tubes and the whole unit isthen placed in a furnace heated to 450560 C. and allowed to remain untilthe frit is sintered into a solid mass. Then the furnace temperature isallowed to drop to 400 C. for a short annealing period. It is thengradually cooled until the sintered assembly can be safely removedwithout cracking. The cutting, grinding, polishing, and mounting maythen be carried out as in Example 1.

Example 3 (a) Spinnerets are made, by the general procedure of Example1, using as a mold in some instances the same glass sheathing and inother instances a metal sheath of comparable size. In all cases, thecapillary tubes used are of 0.1 mm. 1.1). and 0.3 mm. OD. and the cementused is a poly(vinyl chloride) (PVC) plastisol. The assembly is heatedin an oven at ll85 C. until the plastisol fuses. After cooling, thefused assembly of the capillary tubes is readily removed from the sheathand can be used as such, but preferably it is placed in a larger moldand surrounded with additional plastisol and then heated to fuse theplastisol and thereby form a thick protectlve sheath of poly(vinylchloride) about the tube assembly. This unit is then cut transversely,ground, polished and mounted as in Example 1.

(b) The procedure of part (a) is repeated using a plastisol to which athermosetting monomer, such as ethylene glycol dimethacrylate is added.

(0) Part (a) is repeated replacing the plastisol with a resin-formingpoly(vic-epoxide) such as the condensation product of epichlorohydrinand Bis-phenol-A.

(d) The procedure of part (a) is repeated substituting for the plastisola resin-forming rm'xture of (1) an unsaturated polyester obtained from amixture of glycerol, trimethylolethane, phthalic anhydride, and maleicanhydride, (2) styrene or methyl methacrylate, and (3) a freeradicalinitiator.

Example 4 Three woven stainless steel wire screen templates are clampedtogether one above the other with their holes in alignment (FIGURE 7).Then 225 capillary tubes are sealed at one end to form a knob largerthan the screen openings. The other ends are inserted into the holes ofthe several screens and allowed to hang. These ends are then closed andknobs are formed on them. The templates are then released and theassembly is placed in a cylindrical mold (13 mm. ID.) with the templatespositioned in spaced relationship so that one is at each end and thethird is in the middle of the capillary tubes. A cement is introducedaround the tubes in the mold. The cement is hardened and then theassembly is cut at spaced intervals transversely to produce thespinnerets which are then ground and polished as in Example 1.

Example 5 (a) A bundle of a plurality of glass tubes is heated and drawnout lengthwise to form the desired inside diameter capillary hole orchannel in each of the several tubes. The tubes are fused together alongtheir lines of contact. A cement is introduced into the interstitialspaces and hardened. Then the assembly is cut, ground and polished as inExample 1.

(6) Part (a) is modified by inserting the bundle of tubes into a largertube or sheath of glass of the same composition before drawing so thatthe sheath, as well as the tubes inside it, are drawn and fused togethersimultaneously. The interstitial spaces are then filled with cementwhich is hardened. Then the usual cutting, grinding and polishing iseilected as in Example 1.

Example 6 7 Fifteen metal or glass capillary tubes (10 cm. length) .arelaid side-by-side in parallel relationships in contact with each otheron a strip of the pressure-sensitive adhesive layer of a heat-resistantadhesive tape (see FIGURE 8). A cement is disposed between the capillarytubes and the adhesive tape and then is applied to fill thecorresponding grooves. After the cement is set, a unitary wafer having asingle row of small diameter openings is obtained. The spacing betweenopenings can be changed by inserting solid rods between the capillarytubes in the row (FIGURE 9).

' to form a spinneret.

7 The single row wafer may be cut, ground and polished Generally,however, a plurality of such wafers are cemented together beforecutting, grinding and polishing to provide spinnerets having the desirednumber of rows of orifices.

Example 7 Wires of stainless steel or other metal having a low oxidationrate which are highly polished are inserted into slightly largerpassages in capillary tubes of glass having higher coefficient ofexpansion than the glass, one wire being inserted into each glass tube.A plurality of these wire-core/glass tube units are associated inparallel relationship and in contact to form the desired configurationof openings. The wires are clamped under tension at each end of theassembly and the assembly is placed in a furnace where it is heated tothe working point of the glass (e.g. 560 C. for soft lead glass to 1,220C. for hard borosilicate glass). Each tube contracts on the wire and thetubes fuse together at their points of contact. The assembly is cooledslowly to the annealing temperature (e.g. 365 C. for soft solder glassto 525 C. for hard borosilicate glass). Excessively prolonged heatingshould be avoided to prevent oxidation of the wire. When the glassreaches the strain point temperature, the the wires are removed either(1) by a stretching action with constant tension which releases themetal from the capillary or (2) by continuation of the cooling until thewires shrink in diameter sufficiently below the inside diameter of theglass tubes to allow free removal. The assembly is then cemented, cuttransversely, ground, and polished as in Example 1.

I claim:

1. A spinneret consisting of a plurality of contiguous rods disposedparallel to one another having terminal faces at their ends, at leastsome of said rods having capillary passages of uniform diameter of about0.05 to about 0.3 mm., the passages extending between and opening intothe terminal faces of the rods having capillary passages, and the rodsbeing united into an integral unit by cementitious material disposedbetween the outer walls of the rods and filling the spaces between therods.

2. A spinneret as defined in claim 1 in which the rods are cementedwithin an outer sheath.

3. A spinneret as defined in claim 1 in which the rods are cementedwithin an outer sheath provided with a rib projecting radially outwardlytherefrom.

4. A spinneret as defined in claim 1 comprising rods disposed betweenthe rods having capillary passages parallel thereto.

5. A spinneret as defined in claim 1 in which the rods are of glass.

6. A spinneret as defined in claim 1 in which the rods are of metal.

7. A method of making a spinneret which comprises placing a liquidcement in a mold which defines a cylindrical cavity, inserting aplurality of tubes lengthwise into said cylindrical cavity whereby theouter surfaces of said tubes are wetted by said cement, at least some ofsaid tubes having a constant internal passage of about 0.05 to about 0.3mm. in diameter throughout the length of the tubes with the ends sealed,setting the cement to form a unitary structure consisting of said tubesand the set cement disposed between the outer walls of the tubes andfilling the spaces between the tubes, removing said unitary structurefrom said mold and cutting off sections of the structure by cutting ittransversely at intervals spaced along its length.

References Cited in the file of this patent UNITED STATES PATENTS2,354,931 Tolman Aug. 1, 1944 2,372,878 Binns et al. Apr. 3, 19452,798,020 Balz et al. July 2, 1957 2,798,252 Cummings July 9, 19572,799,598 Biefeld July 16, 1957 2,965,925 Dietzsch Dec. 27, 1960 FOREIGNPATENTS 431,096 France June 15, 1911 442,630 France June 24, 1911 30,306Great Britain 1910 253,209 Great Britain June 14, 1926

1. A SPINNERET CONSISTING OF A PLURALITY OF CONTIGUOUS RODS DISPOSEDPARALLEL TO ONE ANOTHER HAVING TERMINAL FACES AT THEIR ENDS, AT LEASTSOME OF SAID RODS HAVING CAPILLARY PASSAGES OF UNIFORM DIAMETER OF ABOUT0.05 TO ABOUT 0.3 MM., THE PASSAGES EXTENDING BETWEEN AND OPENING INTOTHE TERMINAL FACES OF THE RODS HAVING CAPILLARY PASSAGES, AND THE RODSBEING UNITED INTO AN INTEGRAL UNIT BY CEMENTITIOUS MATERIAL DISPOSEDBETWEEN THE OUTER WALLS OF THE RODS AND FILLING THE SPACES BETWEEN THERODS.